The present invention relates generally to the degradation of natural and man-made surfaces as is common in such fields as road milling, mining and construction. More particularly, the present invention relates to increasing the wear resistance of degradation picks commonly used in such processes. In road milling, for example, degradation picks may be secured to the exterior of a rotating drum and brought into engagement with a road surface to remove a layer of the surface in preparation for applying a new layer. In another example, degradation picks may be secured to links of a chain and brought into engagement with the wall of a mine to remove earthen materials. Such uses can wear down a degradation pick quickly.
Degradation picks often comprise a steel body comprising an attachment shank at one end and a super hard tip at an opposing end. As the steel body wears it may fail prior to the super hard tip, prematurely ending the life of the pick. Increasing the wear resistance of degradation picks may extend the life of such picks and thus reduce the frequency that such picks need to be replaced during operation.
Wear to the steel body is especially pronounced on surfaces facing a direction of impact. For example, degradation picks secured to the exterior of a rotating drum may tend to wear on surfaces facing the direction of rotation since these surfaces are most likely to impact a surface.
Consequently, numerous attempts have been made to increase the wear resistance of degradation picks.
One such system is disclosed in U.S. Pat. No. 4,682,987 to Brady et al. which shows heavy duty industrial, mining and general purpose cutting tools comprising hard surface coatings comprising nickel-chromium metal alloy powder and a flux, usually boron and/or silicon. The hard surface is applied in slurry form, dried and then fused in a furnace.
Another such system is disclosed by U.S. Pat. No. 4,725,098 to Beach, which describes a rotary cutting bit for use in mining and excavating applications incorporating an annular groove about a head portion of the bit immediately rearwardly of where a hard tip of the bit is seated and a hardfacing material deposited in the groove in the form of an annular ring.
Another such system is disclosed by U.S. Pat. No. 7,300,115 to Holl et al., which describes a chisel holder for a road milling machine or the like, having a base element supporting a holding neck, a protrusion connected to the base element upstream of the holding neck when viewed in an advancing direction of the tool and a chip breaker formed on the base element and extending, starting at the holding neck, at least partially over the protrusion.
The prior art shows some advancements in increasing the wear resistance of degradation picks; however, it is believed that there is still a need to develop improved wear resistance apparatuses.